The present invention relates to an automatic wrapping material change-over apparatus and more particularly to an apparatus for changing over from a wrapping material being delivered from one bobbin to a wrapping material on the other bobbin in a wrapping material feeding system which draws out a wrapping material from a bobbin on which the wrapping material is wound, then cuts it into a predetermined size and then transfers it to a wrapping-machine.
An apparatus for this type is disclosed in Japanese Patent Laid-Open Publication No. 76696/1974, for example, in which when a wrapping material being drawn out from one bobbin is cut with a knife provided between said one bobbin and a main cutter knife, switching to the other bobbin occurs so that a leading end of the wrapping material from the other bobbin follows a cut end (trailing end) of the wrapping material drawn out from the one bobbin.
However, there is a time delay from the time when the other bobbin begins to rotate for change-over at a predetermined speed until the time when a force end of the wrapping material of said other bobbin begins to follow a cut end of the wrapping material drawn out from said one bobbin. Such a time delay can cause a timing error in the change-over.
Therefore, in the case where such an apparatus is applied to a wrapping material feeding system which cuts a wrapping material with patterns such as a tobacco wrapper into a predetermined size and then supplies it to a wrapping machine, there has been the problem that the pattern becomes out of register at the time of change-over and a defective product results.
In the conventional change-over apparatus, moreover, a change-over knife for cutting wrapping materials on one and the other bobbin at the time of change-over has been another problem.
More particularly, it is necessary that the change-over knife perform its cutting operation in conformity with the timing of a knife of the wrapping material feeding system. In the event of a timing error, wrapping materials having different cut sizes are sent to the wrapping machine at the time of the change-over. However, a conventional cutter knife is constructed so that at the time of cutting operation a knife roller rotates to a knife receiving roller side to cut a material moving therebetween. In this case, there occurs a slight time lag during rotation of the knife roller, so when such a change-over knife is applied to the above change-over apparatus, it is difficult to take timing with the knife of the wrapping material feed system.